Cutting pipes in wellbores using downhole autonomous jet cutting tools

Abstract

A downhole autonomous jet cutting tool includes a main body with a generally cylindrical configuration. The main body includes a locking unit actuable to engage the tool to an inner surface of the pipe, a hydraulic motor with a rotor and a stator, and a rotatable jet cutting nozzle assembly operable to emit a stream of fluid to cut the pipe. The tool also includes a sensor module to detect interactions between the pipe and walls of the wellbore and a control unit in electronic communication with the sensor module and the locking unit. The control unit can identify, based on output of the sensor module, a location where interaction between the pipe and the walls of the wellbore limits downhole movement of the pipe, actuate the locking unit to engage the tool in the inner surface of the pipe, and initiate the stream of fluid from the nozzle assembly.

What is claimed: 
     
       1. A downhole autonomous jet cutting tool configured to cut a pipe in a wellbore, the downhole autonomous jet cutting tool comprising:
 a main body having a generally cylindrical configuration such that the main body limits a downhole flow of fluids past the autonomous jet cutting tool between the autonomous jet cutting tool and the pipe when the tool is deployed in the pipe, the main body comprising:
 a locking unit actuable to engage the tool to an inner surface of the pipe; and 
 a hydraulic motor comprising a rotor and a stator; and 
 a jet cutting nozzle assembly rotatable by the rotor and operable to emit a stream of fluid to cut the pipe; 
 
 a sensor module operable to detect interactions between the pipe and walls of the wellbore, the sensor module comprising at least one of:
 an acoustic transmitter and an acoustic receiver, the acoustic transmitter oriented to send an acoustic signal radially outward relative to an axis of the tool: or 
 an electromagnetic transmitter and an electromagnetic receiver, the electromagnetic transmitter oriented to generate a magnetic field radially outward relative to an axis of the tool; and 
 
 a control unit in electronic communication with the sensor module and the locking unit, the control unit configured to:
 identify, based on output of the sensor module, a location where interaction between the pipe and the walls of the wellbore limits downhole movement of the pipe based on at least one of:
 a change in attenuation of the acoustic signal: or 
 a difference between electromagnetic sensor outputs; 
 
 actuate the locking unit to engage the tool in the inner surface of the pipe; and 
 initiate the stream of fluid from the jet cutting nozzle assembly. 
 
 
     
     
       2. The downhole autonomous jet cutting tool of  claim 1 , wherein the locking unit comprises a packer. 
     
     
       3. The downhole autonomous jet cutting tool of  claim 2 , wherein the locking unit comprises slips. 
     
     
       4. The downhole autonomous jet cutting tool of  claim 1 , wherein the sensor module comprises an acoustic transmitter oriented to send an acoustic signal radially outward relative to an axis of the tool. 
     
     
       5. The downhole autonomous jet cutting tool of  claim 4 , wherein the acoustic signal has a frequency of 20-30 kHz. 
     
     
       6. The downhole autonomous jet cutting tool of  claim 1 , wherein the sensor module comprises an electromagnetic transmitter oriented to generate magnetic field radially outward relative to an axis of the tool. 
     
     
       7. The downhole autonomous jet cutting tool of  claim 1 , wherein the sensor module comprises an ultrasonic sensor. 
     
     
       8. The downhole autonomous jet cutting tool of  claim 1 , wherein the hydraulic motor comprises a rotor embedded inside a stator and the jet cutting nozzle assembly is rotationally fixed to the rotor. 
     
     
       9. The downhole autonomous jet cutting tool of  claim 8 , wherein the body further comprises rubber baffles extending radially outward. 
     
     
       10. The downhole autonomous jet cutting tool of  claim 1 , wherein initiating the stream of fluid from the jet cutting nozzle assembly comprises opening a valve in the main body to permit drilling fluid to enter the main body and exit the jet cutting nozzle assembly. 
     
     
       11. The downhole autonomous jet cutting tool of  claim 10 , wherein the rotor rotates in response to the drilling fluid flowing through the main body. 
     
     
       12. A method for cutting a pipe in a wellbore, the method comprising:
 dropping a downhole autonomous jet cutting tool in a pipe, the downhole autonomous jet cutting tool controlled by a flow rate and configured to identify a location where interaction between the pipe and walls of the wellbore limits a downhole movement of the pipe; 
 sensing the pipe with a sensor module until it reaches the location where interaction between the pipe and the walls of the wellbore limits a downhole movement of the pipe, the sensor module comprising at least one of:
 an acoustic transmitter and an acoustic receiver, the acoustic transmitter oriented to send an acoustic signal radially outward relative to an axis of the tool; or 
 an electromagnetic transmitter and an electromagnetic receiver, the electromagnetic transmitter oriented to generate a magnetic field radially outward relative to an axis of the tool; 
 
 receiving a signal from the sensor module with an identified location based on at least one of:
 a change in attenuation of the acoustic signal; or 
 a difference between electromagnetic sensor outputs; 
 
 sending a signal to the tool to:
 actuate a locking unit to lock the downhole autonomous jet cutting tool in a position proximate to the location where interaction between the pipe and the walls of the wellbore limits a downhole movement of the pipe; and 
 initiate a flow of fluid from a cutting nozzle of the tool to cut the pipe.